Tn Ligands Research Articles

N-acetylgalactosamine-decorated nanoliposomes for targeted delivery of paclitaxel to hepatocellular carcinoma

In this study, we designed and developed a novel asialoglycoprotein receptor (ASGPR)-targeted PEGylated paclitaxel (PTX) nanoliposome for hepatocellular carcinoma (HCC). N-acetylgalactosamine with α configuration (Tn) was synthesized and used as the active targeting ligand. Notably, Tn modified nanoliposomes loaded with PTX (Tn-Lipo-PTX) showed a narrow distribution (PDI=0.18-0.20) with 74±0.36nm of average sizes. Tn-Lipo-PTX has a high encapsulation efficiency of more than 93.0% and 13% of drug loading (DL). Compared with no targeted Con-Lipo-PTX, Tn-Lipo-PTX showed lower and sustained release characteristic in PBS invitro. Tn targeting ASGPR was confirmed by HepG-2cells uptake experiment by fluorescence microscopy analysis. Tn-Lipo-PTX accumulated in HepG-2cells and this process was inhibited by adding Tn ligand, supporting receptor-mediated endocytosis mechanism. MTT assays was implemented in four cell lines. Tn-Lipo-PTX exhibited superior inhibition against ASGPR on over-expressing HepG-2 (IC50=1.93nM). The cell cycle experiments showed that Tn-Lipo-PTX could efficiently increase the percentage of cells arrest in the G2/M phase. Through western blotting analysis, the β-tubulin and cyclin B1 expression in the Tn-Lipo-PTX group were significantly higher compared with other groups and the CDK1 was down-regulated compared with PTX group, which indicated that targeting liposome delivery system could not only change periodic proteins expression, but also improve the killing effect of PTX on hepatocarcinoma cell. Tn-installed PEGylated nanoliposomes have a great potential for targeted cancer chemotherapy.

Crystal structure of bis-[trans-di-chlorido-bis(propane-1,3-di-amine-κ2N,N')chromium(III)] dichromate from synchrotron data.

The structure of the title compound, [CrCl2(tn)2]2[Cr2O7] (tn = propane-1,3-di-amine; C3H10N2), has been determined from synchrotron data. The asymmetric unit contains one CrIII complex cation and half a [Cr2O7]2- anion. In the complex cation, the CrIII ion is coordinated by the four N atoms of two propane-1,3-di-amine (tn) ligands in the equatorial plane and by two Cl atoms in a trans configuration, displaying a distorted octa-hedral coordination sphere. The two six-membered rings in the complex cation have an anti chair-chair conformation with respect to each other. The mean Cr-N(tn) and Cr-Cl bond lengths are 2.09 (1) and 2.320 (2) Å, respectively. The slightly bent dichromate anion is disordered over two sets of sites (occupancy ratio = 0.7:0.3) and has a staggered conformation. The crystal structure is stabilized by inter-molecular hydrogen bonds involving the NH2 groups of the tn ligands as donors and the O atoms of the [Cr2O7]2- anion and chlorido ligands as acceptors.

A supramolecular copper(II) compound with double bridging water ligands: synthesis, crystal structure, spectroscopy, thermal analysis, and magnetism

A complex of composition {[{Cu(NDC)(OH2)(tn)(μ-OH2)}2]·2H2O}∞ (1) and a mononuclear complex salt [Cu(OH2)2(tn)2](NDC)·3H2O (2), where NDC = 2,6-naphthalenedicarboxylate dianion and tn = 1,3-diaminopropane, were simultaneously crystallized from an aqueous solution of the copper(II) naphthalenedicarboxylate—1,3-diaminopropane—methanol system. The crystal and molecular structures of both complexes were determined by single-crystal X-ray diffraction. Compound (1) consists of a supramolecular coordination complex in which the monomeric unit is assembled from a homodinuclear Cu(II) bridged by two water ligands. The Cu(II) centers exhibit distorted octahedral coordination; the equatorial plane is provided by one chelating tn ligand, one NDC2− ligand, one μ-H2O while the axial positions are occupied by H2O and μ-H2O. Strong intra- and/or intermolecular hydrogen bonds, also involving the crystallization water molecules, together with π–π stacking interactions, are involved in building up the supramolecule. The solid structure of compound (2) includes three water molecules of crystallization, the counter ion NDC2−, and a Cu(II) cationic complex in which the metal is six-coordinated in an axially elongated octahedron defined by two chelating tn ligands in the equatorial plane and two water ligands in the axial positions. Thermal analyses of (1) show two significant weight losses corresponding to water molecules (lattice and coordinated), followed by the decomposition of the network.

Crystal structure and spectroscopic properties of trans-dichlorobis(1,3-propane-diamine)chromium(III) perchlorate

The crystal structure of trans-[Cr(tn)2Cl2]ClO4 (tn = 1,3-propanediamine) is determined by a single-crystal X-ray diffraction study at 185 K. The Cr atom is in a slightly distorted octahedral environment coordinated by four nitrogen atoms of two tn ligands and two chlorine atoms in trans position. The orientations of two six-membered rings in the complex cation are in an anti chair-chair conformation with respect to each other. The mean Cr-N(tn) and Cr-Cl bond lengths are 2.0862(2) A and 2.3112(6) A respectively. The ClO4− anions have a slightly distorted tetrahedral geometry with Cl-O lengths and O-Cl-O angles influenced by the hydrogen bonding. The crystal packing is stabilized by several hydrogen bonds. The infrared and electronic absorption spectral properties are also described along with the results of X-ray crystallography.

Crystal Structure and Spectroscopic Properties of trans‐Dibromidobis(propane‐1, 3‐diamine)chromium(III) Perchlorate

AbstractThe structure of trans‐[Cr(tn)2Br2]ClO4 (tn = propane‐1, 3‐diamine) has been determined by a single‐crystal X‐ray diffraction study at 100 K. The complex crystallizes in the space group P$\bar{1}$ of the triclinic system with two mononuclear formula units in a cell of dimensions a = 6.8220(4), b = 8.86199(9), c = 12.6644(8) Å and α = 77.859(7)°, β = 81.765(6)°, and γ = 77.764(7)°. The chromium atom is in a slightly distorted octahedral environment coordinated by four nitrogen atoms of two tn ligands and two bromine atoms in trans positions. The two six‐membered chelate rings in the complex cations are oriented in an anti chair‐chair conformation with respect to each other. The mean Cr–N(tn) and Cr–Br bonds are 2.093(3) and 2.4681(4) Å, respectively. The crystal packing is stabilized by hydrogen bonds. The infrared and electronic absorption spectral properties are consistent with the result of X‐ray crystallography. It is confirmed that the nitrogen atoms of the tn ligand are strong σ‐donors, but the bromido ligands have weak σ‐ and π‐donor properties toward the chromium(III) ion.

New copper(II), nickel(II) and zinc(II) complexes with 1,2,4-triazolo[1,5- a]pyrimidines and the chelating ligand 1,3-propanediamine: An unexpected coordination behavior for the 7-amine-derivative

Five new metal complexes with the metal ions Cu(II), Ni(II) and Zn(II) and containing 1,2,4-triazolo[1,5- a]pyrimidine derivatives and 1,3-propanediamine (tn) are described. The structural morphology of these coordination compounds depends on the triazolopyrimidine derivative used, being mononuclear for 5,7-dimethyl-1,2,4-triazolo[1,5- a]pyrimidine (dmtp) and 5-methyl-1,2,4-triazolo[1,5- a]pyrimidin-7(4 H)-one (HmtpO), and 1D-polymeric for 7-amine-1,2,4-triazolo[1,5- a]pyrimidine (7atp). In the 7atp case, this ligand does not coordinate through N3 atom, as expected, but through N1, N4 and N71 in a bridging fashion. This unexpected coordination mode seems to be induced by the stability of the polynuclear metal complex in presence of tn ligand. All isolated metal complexes have been characterized by single-crystal X-ray diffraction, IR and UV–Vis spectroscopies, and EPR measurements. Moreover, luminescence measurements have been carried out for 7atp ligand and its polynuclear complex with Zn(II).

Trans-Dichloridobis(propane-1,3-diamine-κ2N,N′)chromium(III) perchlorate

In the title compound, [CrCl2(C3H10N2)2]ClO4, the CrIII atom is coordinated equatorially by four N atoms of two propane-1,3-diamine (tn) ligands and axially by two mutually trans Cl atoms, thus displaying a slightly distorted octa­hedral geometry with no crystallographically imposed symmetry. The two six-membered chair chelate rings in the complex cation are in an anti conformation with respect to each other. The Cr—N bond lengths range from 2.0831 (18) to 2.0917 (19) Å, and the Cr—Cl bond lengths are 2.3148 (6) and 2.3135 (6) Å. The perchlorate anions have slightly distorted tetra­hedral geometries. Weak inter­molecular hydrogen bonds involving the tn ligand NH groups as donors, and chloride ligands and anion O atoms as acceptors are observed.

High-dimensional mixed-valence copper cyanide complexes: Syntheses, structural characterizations and magnetism

Reactions of CuCl 2 with different CN complexes in presence of a neutral ancillary ligand lead to two novel mixed-valence Cu complexes [Cu II(bpy)Cu I(CN) 3] n , 1 (bpy = 2,2′-bipyridine) and {[Cu II(tn) 2][Cu I 4(CN) 6]} n 2 (tn = 1,3-diaminopropane). For compound 1, the asymmetric unit involves two Cu ions Cu1 and Cu2 (Cu I and Cu II centres, respectively) which strongly differ in their environments. The Cu1 ion presents a CuC 4 pseudo-tetrahedral geometry, while the Cu2 ion presents a CuN 5 slightly distorted square-pyramidal geometry. The extended structure of 1 is generated by three cyano ligands which differ in their coordination modes. One CN group has a μ 3 coordination mode and bridges two Cu I and one Cu II ion, while the two other CN groups act as μ 2 bridges leading to a sophisticated 3-D structure. As for 1, the asymmetric unit of 2 involves three crystallographically different Cu ions (Cu1A and Cu1B, presumably Cu I centres, and Cu2 presumably Cu II centres). The Cu2 ion presents centrosymmetric CuN 4 coordination environments involving four nitrogen atoms from two bidentate tn ligands; while the Cu1A and Cu1B ions are three coordinated to cyano groups. The structure can be described as formed by 18-membered “[Cu I(CN)] 6” planar metallocycles that are connected to their six neighbors to generate 2-D sheets; these sheets stack forming infinite hexagonal channels in which the [Cu(tn) 2] 2+ units are located. Magnetic measurements show an unexpected weak ferromagnetic coupling ( θ = 0.239(1) K) of the Cu II ions through the long and “a priori diamagnetic” –NC–Cu I–CN– bridges in compound 1 and an essentially paramagnetic behavior in compound 2.

Structural and spectroscopic properties of trans-dichlorobis(2,2-dimethyl-1,3-diaminopropane)chromium(III) chloride

The structure of trans-[CrCl(2)(Me(2)tn)(2)]Cl (Me(2)tn=2,2-dimethylpropane-1,3-diamine) has been determined by a single-crystal X-ray diffraction study at 150K. The analysis reveals that there are two independent Cr(III) complex cations in the structure, one with crystallographic inversion symmetry and the other with two-fold rotation symmetry, which are conformational isomers of each other. In both conformations, the chromium atom adopts a distorted octahedral structure with the four nitrogen atoms of two Me(2)tn ligands occupying the equatorial plane and two chlorine atoms occupying trans-axial positions. The six-membered chelate rings are in stable chair conformations with N-Cr-N angles of 87.03(8) degrees and 88.99(8) degrees . The two chelate rings in the centrosymmetric complex cation 1 are anti, while those in the rotation-symmetric complex cation 2 are in syn conformations. The mean Cr-N and Cr-Cl bond lengths are 2.0922 and 2.3253 A, respectively. The infrared and UV-visible absorption spectra of trans-[CrCl(2)(Me(2)tn)(2)]Cl have also been measured. The resolved band maxima of the electronic d-d spectrum are fitted with a secular determinant for a quartet energy state of the d(3) configuration in a tetragonal field including configurational but neglecting spin-orbit coupling. It is confirmed that the nitrogen atoms of the Me(2)tn ligand have a strong sigma-donor character, but the chloro ligand has weak sigma- and pi-donor properties toward the chromium(III) ion.

Magneto-Structural Correlations in Cu(tn)Cl2 (tn = 1,3-Diaminopropane): Two-Dimensional Spatially Anisotropic Triangular Magnet Formed by Hydrogen Bonds

A novel polymeric one-dimensional compound Cu(tn)Cl2 (tn = 1,3-diaminopropane) was prepared and structurally characterized, and its spectral, magnetic, thermodynamic, and thermal properties were studied. The unique structure shows ladderlike chains composed of Cu(II) atoms and chloro bridging ligands [Cu(-mu(3)-Cl-)Cu2] running along the crystallographic c axis. The coordination geometry about copper (4 + 2) approximates that of a strongly elongated octahedron. The equatorial plane of the coordination octahedron is formed by a chelate N-bonded tn ligand and two chloro ligands. One of the chloro ligands is terminal, and the other one, mu3-Cl-, forms two additional longer bonds to the neighboring copper atoms and thus occupies the axial octahedral positions. The electronic ground state of the Cu(II) ion is of d(z)2 symmetry and suggests the activation of intraladder and interladder Cl...H-N hydrogen bonds as exchange paths that form a two-dimensional pattern of a triangular symmetry. The interaction due to the hydrogen bonds seems to play an important role in molecular packing and magnetic coupling. The studies of magneto-structural correlations including electron paramagnetic resonance measurements and thermodynamic and magnetic properties revealed a two-dimensional character of magnetic correlations with the effective intralayer exchange coupling J/k(B) approximately -3 K. No phase transition to the ordered state has been observed down to 60 mK. Cu(tn)Cl2 with the interlayer coupling J' approximately 10(-3)J and moderate intralayer interaction represents an excellent example of a two-dimensional magnetic system.

New, Multi‐Dimensional Cu(tn)‐[M(CN)6]n– Cyano‐Bridged, Bimetallic Coordination Materials (M = FeII, CoIII, CrIII and tn = 1,3‐Diaminopropane)

AbstractReaction of the [FeIII(CN)6]3– anion with [CuII(tn)(H2O)n]2+ (tn = 1,3‐diaminopropane) affords the compounds [{CuII(tn)}2{FeII(CN)6}]·KCl·5H2O (1), [{CuII(tn)}2{FeII(CN)6}]·4H2O (2), and [{CuII(tnH)2(H2O)2}{FeII(CN)6}]·2H2O (3). Each iron center in 1 and 2 is linked to six copper(II) ions by six cyanide bridges, while each copper ion is linked to three equivalent iron(II) ions. Despite these resemblances, the two compounds present large structural differences caused by two different orientations of the Cu–NC–Fe bridges: compound 1 has a 2D structure which can be described as successions of “Cu4Fe3” defective cubane units, while compound 2 displays a 3D arrangement. Compound 3, in which only two trans‐CN groups are bridging, displays a 1D structure. The tn ligand is chelating in 1, as is usually observed in several parent compounds, but is unexpectedly a bridging ligand in 2 and a terminal protonated tnH+ ligand in 3. Thus, the dimension of the three compounds seems to depend on the tn coordination modes. For the three iron compounds 1–3, the synthetic processes involve the spontaneous reduction of the paramagnetic [FeIII(CN)6]3– anion into the diamagnetic [FeII(CN)6]4– anion. In order to avoid such diamagnetic building blocks, the paramagnetic [Cr(CN)6]3– anion was used instead of the iron(III) analog, leading to [{CuII(tn)}3{CrIII(CN)6}2]·3H2O (4), which is the first 2D ferromagnet containing “‐Cu–NC–Cr‐” linkages. A similar study was performed using the diamagnetic [Co(CN)6]3– anion, leading to [{CuII(tn)}3{CoIII(CN)6}2]·3H2O (5), which is the Co analog of 4. The magnetic properties of compounds 1–3 and 5 show the presence of isolated CuII ions with weak ferromagnetic (1) or antiferromagnetic (2, 3, and 5) interactions. Compound 4 presents a long‐range ferromagnetic ordering below Tc = 9.5 K.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Polynitrile anions as ligands: synthesis, structure and magnetic properties of a new three-dimensional coordination polymer with the 2-dicyanomethylene-1,1,3,3-tetracyanopropanediide (tcpd 2−) bridging ligand

Reaction between CuCl 2 and K 2tcpd (tcpd 2− = {C[CN) 2] 3} 2− = 2-dicyanomethylenc-1,1,3,3-tetracyanopropanediide anion) in presence of the neutral ligand tn (1,3-diaminopropane) in aqueous solution yields the new compound [Cu(tn)(tcpd)] (1) which was characterized by X-ray crystallography. The crystal structure of 1 consists of one [Cu(tn)] 2+ unit and one tcpd 2− anion, both located on general positions. Each Cu atom presents an essentially octahedral coordination with four nitrogen atoms arising from four polynitrile ligands and two nitrogen atoms from the chelating tn ligand. Despite its six nitrile groups potentially bridging, the tcpd ligand acts with a μ 4-bridging mode via four nitrogen atoms of two different C(CN) 2 wings leading to a 3D structure. The magnetic behavior for compound 1 shows a very weak antiferromagnetic coupling of the Cu(II) ions through the NC C CN bridge that can be very well reproduced with a regular S = 1/2 antiferromagnetic chain model with g = 2.108 and J = −0.042.

Low-dimensional compounds containing cyano groups. XII.)copper(II) perchlorate

The title compound, [Cu(C2N3)(C3H10N2)2]ClO4, is made up of [Cu(tn)2{N(CN)2}]+ complex cations (tn is 1,3-diaminopropane) and ClO4- anions. The Cu(II) atom is coordinated by four N atoms of two equatorial tn ligands, with an average distance of 2.041 (7) A, and one nitrile N atom of the dicyanamide anion in an axial position, at a distance of 2.236 (3) A, in a manner approaching square-planar coordination geometry. The complex has C(s) symmetry, with the mirror plane lying through the central C atoms of both tn ligands and the dca ligand. The ClO4- anion might be considered as very weakly coordinated in the opposite axial position [Cu-O = 2.705 (3) A], thus completing the Cu(II) coordination to asymmetric elongated octahedral (4+1+1*). The Cu atom and the perchlorate anion both lie on mirror planes.

First example of atmospheric carbon dioxide uptake by a cyanocomplex: Preparation and structural characterization of Zn 2( tn) 2(CO 3)Ni(CN) 4 · H 2O ( tn = 1,3-diaminopropane)

The aqueous system Zn(II)- tn-[Ni(CN) 4] 2− in contact with air captured carbon dioxide in the form of a carbonato ligand yielded the compound Zn 2( tn) 2(CO 3)Ni(CN) 4 · H 2O by crystallization, which was characterized by elemental analyses, IR spectroscopy and single crystal structure analysis. Its crystal structure is polymeric and is built up of a positively charged framework [ Zn 4 ( tn ) 4 ( CO 3 ) 2 Ni ( CN ) 4 ] n 2 n + , free tetracyanonickellate anions with a nickel atom on the inversion centre and water molecules of crystallization. Two crystallographically different zinc atoms exhibit tetrahedral and penta-coordinations. The zinc atoms are interconnected by two crystallographically independent bridging tn ligands, μ 3 - CO 3 2 - carbonato ligand and one centrosymmetric tetracyanonickellate anion acting as trans-[-NC-Ni(CN) 2-CN-] ligand. The carbonato ligand coordinates three zinc atoms by an unusual mode, two by an unidentate and one by a bidentate fashion with one oxygen donor atom forming two Zn–O coordination bonds.

Molecular assemblies based on tricyanomethanide units and copper(II) ions

New co-ordination polymers of formulae [Cu(tcm) 2(tn)] ( 1) and [Cu(tcm)(tn) 2](tcm) ( 2) (tcm −=tricyanomethanide and tn=1,3-diaminopropane) have been synthesised and characterised by X-ray crystallography and magnetic measurements. For compound 1, the Cu(II) ion presents an elongated and distorted CuN 4N 1N 1 octahedron generated by one chelating tn ligand and by four μ 2-bridging tcm − ligands. The molecular arrangement of 1 can be described as a monodimensional chain of a ladder-like structure in which the Cu⋯Cu distance (7.5157(4) Å) through the tcm − ligand forming the sides is significantly shorter than the corresponding distance observed through that providing the rung (7.7455(4) Å). For compound 2, the Cu(II) ion presents a centrosymmetric elongated CuN 4N 2 octahedron; the equatorial plane is generated by two chelating tn ligands and the two axial positions are filled by two weakly co-ordinated equivalent tcm − units acting as μ 2-bridging ligands. This leads to a monodimensional polymer in which the intrachain Cu⋯Cu distance is 9.1062(2) Å. Magnetic measurements, performed in the temperature range 2–300 K for both compounds, show weak antiferromagnetic interactions for compound 1 while compound 2 obeys a Curie law. The difference between the magnetic behaviours can be explained from the larger intrachain Cu⋯Cu separation in 2 than in 1.

Anionopentaaminecobalt(III) complexes with polyamine ligands. 24. The isolation and structure of mer-[CoCl(tn)(1,5, 9-triazanon-4-ene)]ZnCl 4

The title complex is obtained as a by-product from the synthesis of trans-CoCl 2(tn) 2 + by dioxygen oxidation of Co(II) and the diamine in water at room temperature. A single crystal X-ray structure analysis shows that the tridentate Schiff's Base ligand adopts a meridional configuration and the remaining three octahedral sites are occupied by one bidentate tn ligand and one chloro ligand.

A proton magnetic resonance and preparative study of trimethylenediamine complexes of cobalt(III)

The preparation of trans-[Co(tn)2Cl2]Cl,3.5H2O and [Co(tn)3]Cl3,H2O (1,3-diaminopropane = tn) is shown to proceed more readily and with greater yields when methanol solvent is employed instead of water. The preparation of the new species [Co(tn)2PO4]4H2O, [Co(tn)2(ox)]Cl,H2O, trans-[Co(tn)2(OH)H2O]-(ClO4)2,2H2O, and trans-[Co(tn)2(NH3)2]AsO4,3H2O is reported together with a modified preparation of [Co(tn)2CO3]ClO4. These preparations are discussed in terms of reaction mechanism. The p.m.r, spectra of the above species, trans-[Co(tn)2(NO2)2]NO2, cis-[Co(tn)2(H2O)HPO4]+, and cis-[Co(tn)2(H2O)2]3+ are reported in a range of solvents. The nature of the solvent markedly influences the observed chemical shifts and fine structure. The spectra are interpreted in terms of varying rates of conformational interchange of the tn ligands, and variation of solvent-solute interactions.